[fcstaggered] Fix bug in couplingStencil

See merge request !2962

* use bind instead of bindElement to also get outside scvs


(cherry picked from commit c8f13736)

[fclocalassembler] Revise calculation of residuals

See merge request !2953

* Always calculate full residuals, not just related to fluxes
* only considering fluxes would neglect changes of deflected dofs on source and boundary values

[test][newton][cleanup] Remove time step interface not required anymore from the stationary assembler

See merge request !2959

[test][newton][cleanup] Remove time step interface not required anymore from the stationary assembler

[test][cleanup] Remove parameter dependency

See merge request !2958

This was only needed for global defaults which have been removed for the Newton.

Fixup/dispersion small improvements

See merge request !2941

Dispersion

See merge request !2921

[ci] Restore internal Python environment also for cpp build

See merge request !2940

This is because Dune currently installs Python packages during make for some reason.

[readme] Add repo status badge

See merge request !2939

[python] Fix setup.py to find all sub-packages and add dev dependencies

See merge request !2938

[dune.module] Add version for dune-subgrid

See merge request !2935

[python][cleanup] Run black on setup.py

See merge request !2936

[python] Make bindings work with dune 2.9

See merge request !2934